In dentistry powder jet devices are currently used for applying a fluid stream of abrasive particles, air and water to the tooth structure of a patient, for example for cleaning or pretreating the tooth surfaces.
Generally, a powder jet device may comprise a nozzle head through which the fluid stream can be delivered. Typically the fluid stream contains powder particles which are dispersed and entrained by an air stream guided through a powder containing chamber, and a liquid optionally added to the air/powder mixture, for example through a separate nozzle. In a device of that type used for cleaning tooth surfaces the powder material often comprises dental abrasive particles, and the liquid is normally water.
Examples of a nozzle head for powder jet devices for use in the field of dentistry are described in U.S. Pat. No. 4,676,749 (Mabille) or U.S. Pat. No. 7,762,812 (Pichat et al.). Some powder materials, when delivered through a nozzle of a powder jet device, may tend to block the nozzle. That may be the case if the powder comes into contact with moisture because the powder may become damp and flow less freely than when it is dry. In a more extreme case, the powder may be intended to form a hardenable paste or gel when mixed with the fluid and can, therefore be expected to block the nozzle unless removed. For example, the nozzle head of the device shown in U.S. Pat. No. 4,676,749 has long and curved supply canals having a relatively narrow inner diameter. Such canal may be hard to clean when it comes to powder clogging.
Some powder jet devices for use in the field of dentistry are provided with disposable nozzles as shown in U.S. Pat. No. 4,676,749 for example. Although available devices provide certain advantages there is still a desire for a device which operates reliably with different types of powder and which is relatively easy to maintain. Further such a device desirably is relatively inexpensive and meets hygiene requirements in dentistry.